U.S. patent application number 12/683980 was filed with the patent office on 2011-07-07 for dialysis systems and methods.
This patent application is currently assigned to Fresenius Medical Care Holdings, Inc.. Invention is credited to Martin Joseph Crnkovich, Colin Weaver.
Application Number | 20110163030 12/683980 |
Document ID | / |
Family ID | 43896878 |
Filed Date | 2011-07-07 |
United States Patent
Application |
20110163030 |
Kind Code |
A1 |
Weaver; Colin ; et
al. |
July 7, 2011 |
Dialysis Systems and Methods
Abstract
This invention relates to dialysis systems and methods. In some
implementations, a method includes applying vacuum pressure to a
device of a dialysis system, and then determining, based on a
detected fluid level or measured pressure, whether the device is
functioning properly.
Inventors: |
Weaver; Colin; (Pleasanton,
CA) ; Crnkovich; Martin Joseph; (Walnut Creek,
CA) |
Assignee: |
Fresenius Medical Care Holdings,
Inc.
Waltham
MA
|
Family ID: |
43896878 |
Appl. No.: |
12/683980 |
Filed: |
January 7, 2010 |
Current U.S.
Class: |
210/637 ;
210/120; 73/37 |
Current CPC
Class: |
A61M 2205/18 20130101;
A61M 2205/702 20130101; A61M 1/3641 20140204; G01F 23/296 20130101;
A61M 2205/3331 20130101; A61M 2202/0413 20130101; A61M 1/3627
20130101; A61M 2205/3379 20130101; A61M 2205/3306 20130101; A61M
2205/707 20130101; A61M 1/16 20130101; G01L 19/0092 20130101; A61M
1/1601 20140204; A61M 2205/7536 20130101; A61M 2205/3334 20130101;
A61M 2205/50 20130101; A61M 1/3624 20130101; A61M 2205/3375
20130101; A61M 2205/15 20130101; A61M 1/3639 20130101; A61M 1/3607
20140204; A61M 2205/505 20130101 |
Class at
Publication: |
210/637 ; 73/37;
210/120 |
International
Class: |
B01D 61/32 20060101
B01D061/32; G01M 19/00 20060101 G01M019/00 |
Claims
1. A method, comprising: applying vacuum pressure to an air release
device of a dialysis system, the air release device comprising a
vent; after applying the vacuum pressure to the air release device,
detecting a fluid level within the air release device; and
determining, based on the fluid level within the air release
device, whether the air release device is functioning properly.
2. The method of claim 1, wherein determining whether the air
release device is functioning properly comprises determining
whether the vent of the air release device is functioning
properly.
3. The method of claim 1, wherein the fluid level within the air
release device is detected by a level detector of the dialysis
system, and the level detector is positioned adjacent the air
release device.
4. (canceled)
5. The method of claim 3, wherein the level detector is connected
to a control unit of the dialysis system in a manner such that
signals related to the detected fluid level can be transmitted to
the control unit.
6. The method of claim 1, wherein applying vacuum pressure to the
air release device comprises closing off lines upstream and
downstream of the air release device and activating a pump to draw
fluid out of the air release device.
7. The method of claim 6, wherein closing off the line upstream of
the air release device comprises turning off a pump configured to
circulate fluid through the air release device, and closing off the
line downstream of the air release device comprises clamping the
line, downstream of the air release device.
8. The method of claim 7, wherein the pump that is activated to
draw fluid out of the air release device is an ultrafiltration
pump.
9. The method of claim 7, further comprising misbalancing a
balancing chamber that is in fluid communication with the air
release device to draw the fluid out of the air release device.
10. (canceled)
11. The method of claim 1, wherein the dialysis system comprises
first and second lines connected to the air release device and a
pump configured to circulate fluid from the first line to the air
release device to the second line during dialysis treatment, and
wherein applying vacuum pressure to the air release device
comprises closing off the second line and operating the pump in a
manner to circulate fluid from the second line to the air release
device to the first line.
12. The method of claim 1, further comprising indicating to a user
that the air release device is not functioning properly if, based
on the fluid level within the air release device, it is determined
that the air release device is not functioning properly.
13-14. (canceled)
15. The method of claim 12, wherein indicating to the user that the
air release device is not functioning properly comprises disabling
one or more functions of the dialysis system.
16. The method of claim 1, further comprising applying positive
pressure to the air release device after applying the vacuum
pressure such that air drawn into the air release device by the
vacuum pressure is forced out of the air release device by the
positive pressure.
17. The method Of claim 1, wherein the dialysis system is a
hemodialysis system.
18. The method of claim 17, wherein the method is performed during
hemodialysis treatment.
19. The method of claim 17, wherein the method is performed before
hemodialysis treatment.
20-21. (canceled)
22. A method, comprising: applying vacuum pressure to a device of a
dialysis system, the device comprising a vent; after applying the
vacuum pressure to the device, measuring a pressure within a fluid
line that is fluidly connected to the device; and determining,
based on the measured pressure, whether the device is functioning
properly.
23. The method of claim 22, wherein the measured pressure is
transmitted in the form of a signal to a control unit of the
dialysis system.
24. (canceled)
25. The method of claim 22, wherein the pressure is measured by a
pressure sensor of the dialysis system.
26. The method of claim 25, wherein the pressure sensor comprises a
pressure transducer.
27. (canceled)
28. The method of claim 22, wherein the vacuum pressure is applied
to the air release device by activating a pump.
29. The method of claim 28, wherein the line is in fluid
communication with a dialyzer, a dialysate line is in fluid
communication with the dialyzer, and the pump is an ultrafiltrate
pump that is fluidly connected to the dialysate line.
30. The method of claim 28, wherein the pump is a drug pump that is
configured to introduce fluid into the fluid line when operated in
a first direction and is configured to draw fluid out of the fluid
line when operated in a second direction.
31. The method of claim 30, wherein applying the vacuum pressure
comprises operating the drug pump in the second direction.
32. The method of claim 22, wherein applying vacuum pressure to the
device comprises closing off lines upstream and downstream of the
device and activating a first pump in fluid communication with a
portion of the lines between locations where the lines are closed
off.
33. The method of claim 32, wherein closing off the line upstream
of the device comprises turning off a second pump configured to
circulate fluid through the lines, and closing off the line
downstream of the air release device comprises clamping the line
downstream of the device.
34. (canceled)
35. The method of claim 33, further comprising misbalancing a
balancing chamber that is in fluid communication with the device to
apply vacuum pressure to the device.
36. The method of claim 22, wherein the dialysis system comprises
first and second lines connected to the device and a pump
configured to circulate fluid from the first line to the device to
the second line during dialysis treatment, and wherein applying
vacuum pressure to the device comprises closing off the second line
and operating the pump in a manner to circulate fluid from the
second line to the device to the first line.
37. The method of claim 22, wherein the device is determined to be
functioning improperly if the measured pressure is less than a
desired pressure.
38. The method of claim 37, further comprising indicating to a user
that the device is not functioning properly if the measured
pressure is less than the desired pressure.
39-40. (canceled)
41. The method of claim 38, wherein indicating to the user that the
device is not functioning properly comprises disabling one or more
functions of the dialysis system.
42. The method of claim 22, further comprising applying positive
pressure to the device after applying the vacuum pressure such that
air drawn into the device by the vacuum pressure is forced out of
the device by the positive pressure.
43. The method of claim 22, wherein the device comprises an air
release device.
44. The method of claim 22, wherein the device comprises a pressure
transducer protector.
45. The method of claim 22, wherein the dialysis system is a
hemodialysis system.
46. The method of claim 45, wherein the method is performed during
hemodialysis treatment.
47. The method of claim 45, wherein the method is performed before
hemodialysis treatment.
48-51. (canceled)
52. A dialysis system, comprising: an air release device comprising
a vent; a level detector configured to detect a level of fluid
within the air release device; and a control unit connected to the
level detector, wherein the control unit is configured to determine
whether the air release device is functioning properly based on a
detected fluid level within the air release device when vacuum
pressure is applied to the air release device.
53. A dialysis system, comprising: a device comprising a vent; a
fluid line fluidly connected to the device; a pressure sensor
configured to measure pressure of fluid within the fluid line; and
a control unit connected to the pressure sensor, wherein the
control unit is configured to determine whether the device is
functioning properly based on a measured pressure of fluid within
the fluid line when vacuum pressure is applied to the device.
Description
TECHNICAL FIELD
[0001] This invention relates to dialysis systems and methods.
BACKGROUND
[0002] Dialysis is a treatment used to support a patient with
insufficient renal function. The two principal dialysis methods are
hemodialysis and peritoneal dialysis.
[0003] During hemodialysis ("HD"), the patient's blood is passed
through a dialyzer of a dialysis machine while also passing a
dialysis solution or dialysate through the dialyzer. A
semi-permeable membrane in the dialyzer separates the blood from
the dialysate within the dialyzer and allows diffusion and osmosis
exchanges to take place between the dialysate and the blood stream.
These exchanges across the membrane result in the removal of waste
products, including solutes like urea and creatinine, from the
blood. These exchanges also regulate the levels of other
substances, such as sodium and water, in the blood. In this way,
the dialysis machine acts as an artificial kidney for cleansing the
blood.
[0004] During peritoneal dialysis ("PD"), a patient's peritoneal
cavity is periodically infused with dialysis solution or dialysate.
The membranous lining of the patient's peritoneum acts as a natural
semi-permeable membrane that allows diffusion and osmosis exchanges
to take place between the solution and the blood stream. These
exchanges across the patient's peritoneum, like the continuous
exchange across the dialyzer in HD, result in the removal waste
products, including solutes like urea and creatinine, from the
blood, and regulate the levels of other substances, such as sodium
and water, in the blood.
[0005] Many PD machines are designed to automatically infuse,
dwell, and drain dialysate to and from the patient's peritoneal
cavity. The treatment typically lasts for several hours, often
beginning with an initial drain cycle to empty the peritoneal
cavity of used or spent dialysate. The sequence then proceeds
through the succession of fill, dwell, and drain phases that follow
one after the other. Each phase is called a cycle.
SUMMARY
[0006] In one aspect of the invention, a method includes applying
vacuum pressure to an air release device of a dialysis system. The
air release device includes a vent. After applying the vacuum
pressure to the air release device, a fluid level within the air
release device is detected. Based on the fluid level within the air
release device, it is determined whether the air release device is
functioning properly.
[0007] In another aspect of the invention, a method includes
applying, vacuum pressure to a device of a dialysis system. The
device includes a vent. After applying the vacuum pressure to the
device, a pressure within a fluid line that is fluidly connected to
the device is measured. Based on the measured pressure, it is
determined whether the device is functioning properly.
[0008] In a further aspect of the invention, a method includes
applying vacuum pressure to an air release device of a dialysis
system. The air release device includes a vent. After applying the
vacuum pressure to the air release device, a fluid level within the
air release device is detected, and if the fluid level within the
air release device exceeds a given level after applying the vacuum
pressure to the air release device, a user is informed that the air
release device is not functioning properly.
[0009] In an additional aspect of the invention, a method includes
applying vacuum pressure to a device of a dialysis system. The
device includes a vent. After applying the vacuum pressure to the
device, a pressure within a fluid line that is fluidly connected to
the device is measured, and if the measured pressure is less than a
certain pressure, a user is informed that the device is not
functioning properly.
[0010] In yet another aspect of the invention, a dialysis system
includes an air release device with a vent, a level detector
configured to detect a level of fluid within the air release
device, and a control unit connected to the level detector. The
control unit is configured to determine whether the air release
device is functioning properly based on a detected fluid level
within the air release device when vacuum pressure is applied to
the air release device.
[0011] In a further aspect of the invention, a dialysis system
includes a device with a vent, a fluid line fluidly connected to
the device, a pressure sensor configured to measure pressure of
fluid within the fluid line, and a control unit connected to the
pressure sensor. The control unit is configured to determine
whether the device is functioning properly based on a measured
pressure of fluid within the fluid line when vacuum pressure is
applied to the device.
[0012] Implementations can include one or more of the following
features.
[0013] In some implementations, determining whether the air release
device is functioning properly includes determining whether the
vent of the air release device is functioning properly.
[0014] In certain implementations, the fluid level within the air
release device is detected by a level detector of the dialysis
system, and the level detector is positioned adjacent the air
release device.
[0015] In some implementations, the level detector includes a
transmitter configured to emit ultrasonic signals and a receiver
adapted to receive ultrasonic signals.
[0016] In certain implementations, the level detector is connected
to a control unit of the dialysis system in a manner such that
signals related to the detected fluid level can be transmitted to
the control unit.
[0017] In some implementations, applying vacuum pressure to the air
release device includes closing off lines upstream and downstream
of the air release device and activating a pump to draw fluid out
of the air release device.
[0018] In certain implementations, closing off the line upstream of
the air release device includes turning off a pump configured to
circulate fluid through the air release device, and closing off the
line downstream of the air release device includes clamping the
line downstream of the air release device.
[0019] In some implementations, the pump that is activated to draw
fluid out of the air release device is an ultrafiltration pump.
[0020] In certain implementations, the method further includes
misbalancing a balancing chamber that is in fluid communication
with the air release device to draw the fluid out of the air
release device.
[0021] In some implementations, applying vacuum pressure to the air
release device includes closing off lines upstream and downstream
of the air release device and activating a pump to draw fluid out
of the air release device.
[0022] In certain implementations, the dialysis system includes
first and second lines connected to the air release device and a
pump configured to circulate fluid from the first line to the air
release device to the second line during dialysis treatment, and
applying vacuum pressure to the air release device includes closing
off the second line and operating the pump in a manner to circulate
fluid from the second line to the air release device to the first
line.
[0023] In some implementations, the method further includes
indicating to a user that the air release device is not functioning
properly if, based on the fluid level within the air release
device, it is determined that the air release device is not
functioning properly.
[0024] In certain implementations, indicating to the user that the
air release device is not functioning properly includes emitting a
visual signal.
[0025] In some implementations, indicating to the user that the air
release device is not functioning properly includes emitting an
audio signal.
[0026] In certain implementations, indicating to the user that the
air release device is not functioning properly includes disabling
one or more functions of the dialysis system.
[0027] In some implementations, the method further includes
applying positive pressure to the air release device after applying
the vacuum pressure such that air drawn into the air release device
by the vacuum pressure is forced out of the air release device by
the positive pressure.
[0028] In certain implementations, the dialysis system is a
hemodialysis system.
[0029] In some implementations, the method is performed during
hemodialysis treatment.
[0030] In certain implementations, the method is performed before
hemodialysis treatment.
[0031] In some implementations, the fluid within the air release
device includes saline.
[0032] In certain implementations, the fluid within the air release
device includes blood.
[0033] In some implementations, the air release device includes a
drip chamber and a pressure sensor assembly extending from the drip
chamber, and the pressure sensor assembly includes a transducer
protector that houses the vent.
[0034] In certain implementations, determining whether the air
release device is functioning properly includes determining whether
the vent of the transducer protector is functioning properly.
[0035] In some implementations, detecting the fluid level within
the air release device includes detecting a fluid level within the
drip chamber.
[0036] In certain implementations, the measured pressure is
transmitted in the form of a signal to a control unit of the
dialysis system.
[0037] In some implementations, the control unit is a
microprocessor.
[0038] In certain implementations, the pressure is measured by a
pressure sensor of the dialysis system.
[0039] In some implementations, the pressure sensor includes a
pressure transducer.
[0040] In certain implementations, the pressure sensor is attached
to a dialysis machine of the dialysis system and is aligned with
the fluid line.
[0041] In some implementations, the vacuum pressure is applied to
the air release device by activating a pump.
[0042] In certain implementations, the line is in fluid
communication with a dialyzer, a dialysate line is in fluid
communication with the dialyzer, and the pump is an ultrafiltrate
pump that is fluidly connected to the dialysate line.
[0043] In some implementations, the pump is a drug pump that is
configured to introduce fluid into the fluid line when operated in
a first direction and is configured to draw fluid out of the fluid
line when operated in a second direction.
[0044] In certain implementations, applying the vacuum pressure
includes operating the drug pump in the second direction.
[0045] In some implementations, applying vacuum pressure to the
device includes closing off lines upstream and downstream of the
device and activating a first pump in fluid communication with a
portion of the lines between locations where the lines are closed
off.
[0046] In certain implementations, closing off the line upstream of
the device includes turning off a second pump configured to
circulate fluid through the lines, and closing off the line
downstream of the air release device includes clamping the line
downstream of the device.
[0047] In some implementations, the first pump is an
ultrafiltration pump.
[0048] In certain implementations, the method further includes
misbalancing a balancing chamber that is in fluid communication
with the device to apply vacuum pressure to the device.
[0049] In some implementations, the dialysis system includes first
and second lines connected to the device and a pump configured to
circulate fluid from the first line to the device to the second
line during dialysis treatment, and wherein applying vacuum
pressure to the device includes closing off the second line and
operating the pump in a manner to circulate fluid from the second
line to the device to the first line.
[0050] In certain implementations, the device is determined to be
functioning improperly if the measured pressure is less than a
desired pressure.
[0051] In some implementations, the method further includes
indicating to a user that the device is not functioning properly if
the measured pressure is less than the desired pressure.
[0052] In certain implementations, the method further includes
applying positive pressure to the device after applying the vacuum
pressure such that air drawn into the device by the vacuum pressure
is forced out of the device by the positive pressure.
[0053] In some implementations, the device includes an air release
device.
[0054] In certain implementations, the device includes a pressure
transducer protector.
[0055] Implementations can include one or more of the following
advantages.
[0056] In some implementations, the device (e.g., the air release
device) is tested before treatment begins. As a result, if the
device is determined to be functioning improperly, the operator of
the system can replace or repair the device prior to treatment such
that treatment is not interrupted. Testing the device prior to
treatment (e.g., during priming of the dialysis system) also helps
to ensure that the operator of the dialysis system is present to
promptly replace or repair the device. For example, in many
clinical settings, the operator of the dialysis system tends to
walk away from the system after the automated portion of the
treatment begins. Thus, in such clinical settings, testing the
device prior to treatment helps to ensure that the operator of the
system is around to correct any identified problem with the
device.
[0057] In certain implementations, the device (e.g., air release
device) is periodically tested during treatment. As a result,
damage occurring to the device during treatment can be detected. In
the case of an air release device, for example, this technique can
be used to detect whether the vent of the air release device has
become clogged, which can negatively affect the ability of the vent
to vent air or other gases from the air release device to the
atmosphere. If the device is determined to be functioning
improperly, the operator can quickly take measures to help ensure
that treatment is not negatively affected by the malfunctioning
device. For example, in implementation in which the device is an
air release device of a hemodialysis system, the user can avoid the
introduction of additional fluids (e.g., drugs) that might contain
air or other gases into the blood circuit, or the user can
temporarily stop the treatment and replace or repair the air
release device. This can help to ensure that air is not introduced
into the patient during treatment.
[0058] In some implementations, the testing of the device (e.g.,
the air release device) is automated. As a result, the operator of
the system can identify whether the device is functioning
improperly with little effort. This helps to ensure that the
operator of the system does not overlook a defective or otherwise
malfunctioning device.
[0059] In certain implementations, certain functions of the
dialysis system are disabled upon determining that the device
(e.g., the air release device) is not functioning properly. The
disabled functions can, for example, be functions required to
perform treatment such that treatment cannot be performed until the
malfunctioning device has been repaired or replaced. In some
implementations, for example, a pump of the machine can be disabled
to prevent the machine from circulating fluid until the device has
been replaced or repaired. This helps to ensure that the treatment
of the patient is not negatively affected by the malfunctioning
device.
[0060] Other aspects, features, and advantages will be apparent
from the description, drawings, and claims.
DESCRIPTION OF DRAWINGS
[0061] FIG. 1 is a front perspective view of a hemodialysis
system.
[0062] FIG. 2 is a front perspective view of the hemodialysis
system of FIG. 1 with a door of a module of the hemodialysis system
in an open position to expose a blood component set secured to the
module.
[0063] FIG. 3 is a front view of the blood component set of the
hemodialysis system of FIGS. 1 and 2.
[0064] FIG. 4 is a rear view of the blood component set of the
hemodialysis system of FIGS. 1 and 2.
[0065] FIG. 5 is a front view of an air release device of the blood
component set of FIGS. 3 and 4.
[0066] FIG. 6 is a top view of the air release device of FIG.
5.
[0067] FIG. 7 is a bottom view of the air release device of FIG.
5.
[0068] FIG. 8 is a top perspective view of the air release device
of FIG. 5, with the air release device lying horizontally on its
rear surface.
[0069] FIG. 9 is a front view of the hemodialysis system of FIG. 1
with the door of the module of the system in an open position and
the blood component set removed from the module to expose blood
pumping and monitoring instruments on the front face of the
module.
[0070] FIG. 10 is a schematic of fluid flow through the blood
circuit and dialysate circuit of the hemodialysis system of FIG.
1.
[0071] FIG. 11 is a schematic of fluid flow through the blood
circuit and dialysate circuit of the hemodialysis system of FIG. 1
when the hemodialysis system is connected to a patient for
treatment.
[0072] FIG. 12 is a schematic of a hemodialysis system including a
blood component set with a pressure sensing blood line having a
transducer protector connected to a pressure transducer of a
hemodialysis machine.
DETAILED DESCRIPTION
[0073] Referring to FIGS. 1 and 2, a hemodialysis system 100
includes a hemodialysis machine 102 to which a disposable blood
component set 104 that forms a blood circuit is connected. During
hemodialysis, arterial and venous patient lines 106, 108 of the
blood component set 104 are connected to a patient and blood is
circulated through various blood lines and components, including a
dialyzer 110, of the blood component set 104. At the same time,
dialysate is circulated through a dialysate circuit formed by the
dialyzer 110 and various other dialysate components and dialysate
lines connected to the hemodialysis machine 102. Many of these
dialysate components and dialysate lines are located inside the
housing of the hemodialysis machine 102, and are thus not visible
in FIGS. 1 and 2. The dialysate passes through the dialyzer 110
along with the blood. The blood and dialysate passing through the
dialyzer 110 are separated from one another by a semi-permeable
structure (e.g., a semi-permeable membrane and/or semi-permeable
microtubes) of the dialyzer 110. As a result of this arrangement,
toxins are removed from the patient's blood and collected in the
dialysate. The filtered blood exiting the dialyzer 110 is returned
to the patient. The dialysate that exits the dialyzer 110 includes
toxins removed from the blood and is commonly referred to as "spent
dialysate." The spent dialysate is routed from the dialyzer 110 to
a drain.
[0074] One of the components of the blood component set 104 is an
air release device 112. The air release device 112 includes a
self-sealing vent assembly 114 (shown in FIG. 5) that allows air to
pass therethrough while inhibiting (e.g., preventing) liquid from
passing therethrough. As a result, if blood passing through the
blood circuit during treatment contains air, the air will be vented
to atmosphere as the blood passes through the air release device
112. The air release device 112 can be tested prior to or during
treatment to ensure that it is functioning properly. To test the
air release device 112, a vacuum is applied to a chamber 116 (shown
in FIG. 5) of the air release device 112 and the liquid level
(e.g., saline level or blood level) within the chamber 116 of the
air release device 112 and/or the pressure within a portion of the
blood circuit including the air release device 112 is monitored.
If, in response to the applied vacuum, the liquid level in the
chamber 116 of the air release device 112 does not substantially
drop and/or the pressure in the portion of the blood circuit
including the air release device 112 falls below a certain value,
this indicates that an insufficient amount of air is entering the
release device 112, which further indicates that the vent assembly
114 of the air release device 112 is likely blocked. In response,
the operator can replace or repair the improperly functioning air
release device 112 or the entire blood component set 104 of which
the air release device 112 is a part. This helps to ensure that any
air within the blood circuit during treatment is allowed to escape
to atmosphere before reaching the patient. Methods of testing the
air release device 112 will be described in greater detail
below.
[0075] Still referring to FIGS. 1 and 2, the hemodialysis machine
102 includes a touch screen 118 and a control panel 120. The touch
screen 118 and the control panel 120 allow the operator to input
various different treatment parameters to the hemodialysis machine
102 and to otherwise control the hemodialysis machine 102. In
addition, the touch screen 118 serves as a display to convey
information to the operator of the hemodialysis system 100. A
speaker 122 is positioned below the touch screen 118 and functions
to provide audio signals to the operator of the system 100. Thus,
the hemodialysis machine 102 is capable of providing both visual
alerts via the touch screen 118 and audio alerts via the speaker
122 to the operator of the system 100 during use. While the speaker
122 has been described as being positioned below the touch screen
118, it should be appreciated that the speaker 122 could be
positioned at any of various other locations on the hemodialysis
machine 102.
[0076] As shown in FIGS. 1 and 2, a dialysate container 124 is
connected to the hemodialysis machine 102 via a dialysate supply
line 126. A drain line 128 and an ultrafiltration line 129 also
extend from the hemodialysis machine 102. The dialysate supply line
126, the drain line 128, and the ultrafiltration line 129 are
fluidly connected to the various dialysate components and dialysate
lines inside the housing of the hemodialysis machine 102 that form
part of the dialysate circuit. During hemodialysis, the dialysate
supply line 126 carries fresh dialysate from the dialysate
container 124 to the portion of the dialysate circuit located
inside the hemodialysis machine 102. As noted above, the fresh
dialysate is circulated through various dialysate lines and
dialysate components, including the dialyzer 110, that form the
dialysate circuit. As the dialysate passes through the dialyzer
110, it collects toxins from the patient's blood. The resulting
spent dialysate is carried from the dialysate circuit to a drain
via the drain line 128. When ultrafiltration is performed during
treatment, a combination of the spent dialysate and excess fluid
drawn from the patient is carried to the drain via the
ultrafiltration line 129.
[0077] The blood component set 104 is secured to a module 130
attached to the front of the hemodialysis machine 102. The module
130 includes a blood pump 132 capable of driving blood through the
blood circuit. The module 130 also includes various other
instruments capable of monitoring the blood flowing through the
blood circuit. The module 130 includes a door 131 that when closed,
as shown in FIG. 1, cooperates with the front face of the module
130 to form a compartment sized and shaped to receive the blood
component set 104. In the closed position, the door 131 presses
certain blood components of the blood component set 104 against
corresponding instruments exposed on the front face of the module
130. As will be described in greater detail below, this arrangement
facilitates control of the flow of blood through the blood circuit
and monitoring of the blood flowing through the blood circuit.
[0078] FIGS. 3 and 4 are front and back views, respectively, of the
blood component set 104. As shown in FIGS. 3 and 4, the blood
component set 104 includes various different blood lines and blood
components, including the air release device 112, that are secured
to a carrier body 134. The carrier body 134 forms a series of
apertures and recesses for capturing and retaining the various
blood lines and components. The carrier body 134 includes a
recessed portion (shown on the left side of FIG. 3 and the right
side of FIG. 4) and a flat portion (shown on the right side of FIG.
3 and the left side of FIG. 4). The recessed portion is configured
to retain most of the blood components while the flat portion is
configured to hold the dialyzer 110. As shown in FIG. 4,
projections 135 extend from the rear surface of the carrier body
134. These projections 135 cooperate with recessed regions formed
in the front face of the module 130 to secure the carrier body 134
and thus the blood component set 104 to the module 130. The
projections 135 also help to properly align the blood component set
104 with the front face of the module 130 such that the various
blood components and blood lines of the blood component set 104
operatively mate with associated instruments on the front face of
the module 130 when the blood component set 104 is secured to the
module 130 and the door 131 of the module 130 is closed.
[0079] The air release device 112 is retained in an aperture formed
in the carrier body 134. The air release device 112 can, for
example, be snapped into the aperture formed in the carrier body
134. In some implementations, fingers extending from the carrier
body 134 extend part way around the air release device 112 to
retain the air release device 112 securely to the carrier body 134.
The air release device 112, as noted above, allows gas, such as
air, to escape from blood in the blood circuit and out of the
chamber 116 of the air release device 112 through the vent assembly
114 positioned at the top of the chamber 116.
[0080] Referring to FIGS. 5-8, which illustrate various different
views of the air release device 112, the air release device 112 has
a housing 136 that forms the air release chamber 116. The chamber
116 has a bottom region 138 and a top region 140. An entry port 142
and an exit port 144 are formed in a bottom surface of the housing
136. A filter 145 is positioned at the exit port 144. The filter
145 inhibits (e.g., prevents) blood clots in the chamber 116 from
exiting the air release device 112. A dam 146 extends upward from
the bottom surface or floor of the housing between the ports 142,
144 so that all fluid entering the entry port 142 flows over the
dam 146 before flowing out the exit port 144.
[0081] The self-sealing vent assembly 114 of the air release device
112 is located at the top of the housing 136. The vent assembly 114
is designed to permit air to escape from the chamber 116 while
inhibiting (e.g., preventing) liquid from escaping from the chamber
116. The vent assembly 114 includes a micro-porous membrane 148 and
a vent structure 150. The micro-porous membrane 148 allows gas
(e.g., from air bubbles in the blood or other circulating liquids)
to vent from the chamber 116 to the atmosphere. At the same time,
pores in the micro-porous membrane 148 are small enough to keep
foreign particles and organisms from entering the chamber 116 from
the outside air. In some implementations, the membrane 148 includes
a hydrophobic material, such as polytetrafluoroethylene (PTFE)
(e.g., expanded polytetrafluoroethylene (ePTFE)). In certain
implementations, the membrane 148 is a fibrous carrier with a
matted and woven layer on top of which ePTFE or other micro-porous
material is applied. The hydrophobic micro-porous membrane 148
keeps liquid from leaking out of the chamber 116 when the chamber
116 is substantially filled with liquid and allows air to pass
therethrough. The membrane 148 has an average pore size of about
0.05 microns to about 0.45 microns (e.g., about 0.22 microns, about
0.2 microns). Suitable membranes are available from Pall
Corporation, East Hills, N.Y., under the Versapor.RTM. mark and
from W. L. Gore & Associates, Inc., Newark, Del.
[0082] The vent structure 150 automatically seals shut if it gets
wet. As a result, the vent structure 150 can prevent blood from
escaping from the chamber 116 or other liquids from entering the
chamber 116 in the event of the membrane 148 rupturing. In some
implementations, the vent structure 150 is a solid porous block,
having an average, pore size of about 15 micron to about 45
microns, that allows air to pass through and escape from the
chamber. In certain implementations, the vent structure 150 is
formed of a blend of polyethylene (e.g., high density polyethylene
(HDPE)) and carboxymethylcellulose (CMC), a blend of polystyrene
and methyl-ethyl-cellulose or of polypropylene- or
polyethylene-based porous material. Such materials are available
from Porex Corporation, Fairburn, Ga. One such product contains 90%
by weight polyethylene and 10% by weight carboxymethylcellulose
with an average pore size of about 30 microns to about 40 microns.
However, other percentages of the materials can be used, as well as
other materials and other pore sizes. For example, the vent
structure 150 can include about 80% to about 95% by weight high
density polyethylene and about 5% to about 20% by weight
carboxymethylcellulose.
[0083] When the vent structure 150 comes into contact with liquid,
the swelling agent (e.g., cellulose component, such as
carboxymethylcellulose) of the vent structure expands, thereby
closing off the pores in the polymer component (e.g., high density
polyethylene) of the vent structure 150. The vent structure 150 is
mounted adjacent to and just above the membrane 148 so that the
membrane 148 is located between the vent structure 150 and the
chamber 116. The vent structure 150 inhibits (e.g., prevents)
condensation from accumulating on and contacting the membrane 148.
For example, if condensation begins to build up on the vent
structure 150, the pores of the vent structure close thereby
inhibiting the condensation from reaching the membrane 148. The
vent structure 150 similarly inhibits (e.g., prevents) liquid from
escaping from the chamber 116. If, for example, the membrane 148
were to rupture and liquid were to pass through the ruptured
membrane 148, the pores of the vent structure 150 would
automatically close upon coming into contact with the liquid.
[0084] When the chamber 116 of the air release device 112 contains
blood, inhibiting (e.g., preventing) the protein in the blood from
accumulating on the membrane 148 can maintain the hydrophobic
characteristic of the membrane 148. Whole blood can be kept from
the membrane 148 by providing saline between the blood and the
membrane 148. The height and shape of the chamber 116 are
sufficient to maintain a blood/saline interface 152, and thus
inhibits (e.g., prevents) the saline above the interface 152 from
substantially mixing with blood below the interface 152.
[0085] Suitable air release devices are described in greater detail
in U.S. Patent Application Publication No. 2009/0071911, entitled
"Safety Vent Structure for Extracorporeal Circuit," which is
incorporated by reference herein.
[0086] Referring back to FIGS. 3 and 4, arterial and venous
pressure sensor capsules 154, 156 are also positioned in apertures
formed in the carrier body 134 of the blood component set 104. Each
of the pressure sensor capsules 154, 156, as shown in FIG. 4,
includes an annular rigid member 155, 157 to which a thin membrane
159, 161 is secured. The annular rigid members 155, 157 and the
thin membranes 159, 161 of the capsules 154, 156 together form a
pressure sensor chamber through which blood flows during use. When
the blood component set 104 is secured to the front face of the
module 130 of the hemodialysis machine 102, the thin membranes 159,
161 of the pressure sensor capsules 154, 156 face the front face of
the module 130. The pressure within the pressure sensor chambers
can be detected through the thin membranes 159, 161 by pressure
sensors (e.g., a pressure transducers) on the front face of the
module 130 during use. Suitable capsules are described further in
U.S. Pat. No. 5,614,677, "Diaphragm Gage for Measuring the Pressure
of a Fluid," which is incorporated herein by reference.
[0087] The arterial patient line 106, as shown in FIGS. 3 and 4, is
contained within a recess formed in the carrier body 134. One end
of the arterial patient line 106 is fluidly connected to an artery
of a patient during treatment. The arterial patient line 106 is
also fluidly connected to the pressure sensor capsule 154. The
arterial patient line 106 extends along the recess to a first pump
line adaptor 158, which connects the arterial patient line 106 to
one end of a U-shaped pump line 160. The other end of the pump line
160 is connected to a second pump line adaptor 162, which is
fluidly connected to a dialyzer inlet line 164. The dialyzer inlet
line 164 is connected via a tube adaptor to a blood entry port 166
of the dialyzer 110. A blood exit port 168 of the dialyzer 110 is
connected to another tube adaptor, which connects the dialyzer 110
to a dialyzer outlet line 170. The pressure sensor capsule 156 is
positioned along the dialyzer outlet line 170, upstream of the air
release device 112. The pressure sensor capsule 156 is fluidly
connected to the entry port 142 (shown in FIG. 5) of the air
release device 112. The pressure sensor capsule 156 allows blood
pressure on the venous side of the dialyzer 110 to be sensed by a
mating pressure sensor on the front face of the module 130 during
treatment. The venous patient line 108 is connected to the exit
port 144 (shown in FIG. 5) of the air release device 112. The
venous patient line 108 extends from the air release device 112 and
is fluidly connected to a vein of a patient during treatment.
[0088] Still referring to FIGS. 3 and 4, in addition to the blood
lines forming the main blood circuit described above, a saline
delivery line 172 and a drug delivery line 174 are connected to the
blood circuit for introducing saline and drugs (e.g., heparin) into
the blood circuit. The saline delivery line 172 is connected to a
saline bag 176. The drug delivery line 174 is connected to a
syringe 178 that contains a drug. The saline delivery line 172 is
connected to the first pump line adaptor 158, and the drug delivery
line 174 is connected to the second pump line adaptor 162.
[0089] The various blood lines, the saline delivery line 172, and
the drug delivery line 174 can be formed of any of various
different medical grade materials. Examples of such materials
include. PVC, polyethylene, polypropylene, silicone, polyurethane,
high density polyethylene, nylon, ABS, acrylic, isoplast,
polyisoprene, and polycarbonate. In some implementations, the blood
component carrier body 134 is formed of PVC, polyethylene,
polypropylene, polystyrene, and/or high density polyethylene. The
various blood lines, the saline delivery line 172, and the drug
delivery line 174 are typically retained within recessed channels
formed in the carrier body 134. The recessed channels can have a
diameter equal to or slightly less than the diameters of the lines
so that the lines are retained within the channels with a friction
fit. Alternatively or additionally, any of various other techniques
can be used to secure the lines to the carrier body 134. For
example, mechanical attachment devices (e.g., clips or clamps) can
be attached to the carrier body 134 and used to retain the lines.
As another example, the lines can be adhered to or thermally bonded
to the carrier body 134.
[0090] Suitable blood component sets and their related components
are described in greater detail in U.S. Patent Application
Publication No. 2009/0101566, entitled "Dialysis Systems and
Related Components," which is incorporated by reference herein.
[0091] FIG. 9 is an enlarged front view of the module 130 of the
hemodialysis machine 102 with the door 131 of the module 130 open
and the blood component set 104 removed from the module 130. As
shown in FIG. 9, the blood pump 132 extends from the front face of
the module 130 of the hemodialysis machine 102. The blood pump 132
is a peristaltic pump and is arranged so that the U-shaped pump
line 160 extending laterally from the carrier body is positioned
around the peristaltic pump when the blood component set 104 is
secured to the front face of the module 130.
[0092] The module 130 of the hemodialysis machine 102 also includes
a level detector 182 that aligns with the air release device 112
when the blood component set 104 is secured to the front face of
the module 130. The level detector 182 is adapted to detect the
level of liquid (e.g., blood and/or saline) within the air release
device 112. The door 131 of the module 130 includes a projection
183 that compresses the air release device 112 against the level
detector 182 when the blood component set 104 is secured to the
front face of the module 130 and the door 131 is closed. The
projection 183 includes a recessed region adapted to receive the
rounded exterior surface of the air release device 112. The
recessed region helps to ensure that the air release device 112 is
properly positioned with respect to the level detector 182 when the
door 131 is closed. The level detector 182 is a cylindrical member
having a relatively soft tip (e.g., a sponge tip) that contacts the
outer surface of the air release device 112 when the door 131
presses the air release device 112 against the level detector 182.
The tip of the level detector 182 includes an ultrasound signal
transmitter and receiver for determining the level of liquid in the
air release device 112. During use, the transmitter emits an
ultrasonic signal that reflects off of the contents in the air
release chamber 112. The reflected signal is then detected by the
receiver. The reflected signal can be used to determine the
contents in the air release chamber 116 at the level of the level
detector 182. The receiver can, for example, be adapted to
distinguish between liquid, air, and a combination of liquid and
air (e.g., foam). As a result, the level detector 182 can detect
when the blood level within the chamber 116 drops due to the entry
of air into the chamber 116.
[0093] While the tip of the level detector 182 has been described
as including a separate 30, transmitter and receiver, in some
implementations, the level detector includes a transmitter/receiver
that performs both functions of transmitting and receiving.
[0094] Still referring to FIG. 9, the module 130 of the
hemodialysis machine 102 also includes arterial and venous pressure
transducers 184, 186 that align with the pressure sensor capsules
154, 156 of the blood component set 104 when the blood component
set 104 is secured to the front face of the module 130 and the door
131 of the module 130 is closed. The pressure transducers 184, 186
are capable of measuring the pressure of blood flowing through the
capsules 154, 156. The pressure transducers 184, 186 are
cylindrical members having substantially flat surfaces exposed on
the front face of the module 130. The door 131 includes
spring-loaded plungers 187, 189 that compress the annular rigid
members 155, 157 (shown in FIG. 4) of the pressure sensor capsules
154, 156 between the door 131 and the front face of the module 130
when the blood component set 104 is secured to the front face of
the module 130 and the door 131 is closed. As a result, the
membranes 159, 161 (shown in FIG. 4) of the pressure sensor
capsules 154, 156 are pressed against the pressure transducers 184,
186 and a seal is created between the perimeter of each of the thin
membranes 159, 161 and the front face of the module 130. The
central regions of the membranes 159, 161 of the pressure sensor
capsules 154, 156 contact the flat surfaces of the pressure
transducers 184, 186. As the fluid pressure changes within the
pressure sensor capsules 154, 156, the amount of pressure applied
to the pressure transducers 184, 186 by the pressure sensor
capsules 154, 156 also changes. The pressure transducers 184, 186
are capable of detecting these pressure changes during use.
[0095] An air bubble detector 188 also extends from the front face
of the module 130. When the blood component set 104 is secured to
the front face of the module 130, the venous patient line 108
passes through (e.g., is threaded through) the air bubble detector
188. The air bubble detector 188 includes a housing that forms a
channel in which the venous patient line 108 is received. The door
131 of the module 130 includes a fin 191 that presses the venous
patient line 108 into the channel of the housing and against a
sensor of the air bubble detector 188 when the door 131 is closed.
The air bubble detector 188 is capable of detecting air bubbles
within the venous patient line 108. In some implementations, the
air bubble detector 188 is an optical detector. The OPB 350 bubble
detector made by Optek can, for example, be used. Any of various
other types of optical detectors can alternatively or additionally
be used. Similarly, other types of sensors, such as sensors
utilizing ultrasound technology can be used as the air bubble
detectors.
[0096] Downstream of the air bubble detector 188, the venous
patient line 108 passes through (e.g., is threaded through) an
occluder or clamp 190. Similar to the air bubble detector 188, the
occluder 190 has a housing that forms a channel in which the venous
patient line 108 is received. The door 131 of the module 130
includes a fin 193 that presses the venous patient line 108 into
the channel of the housing of the occluder 190 when the door 131 is
closed. The occluder 190 is configured to crimp the portion of the
venous patient line 108 disposed therein to prevent blood from
passing through the venous patient line 108 when activated. The
occluder 190 can, for example, be connected to the air bubble
detector 188 so that the occluder 190 can be activated when the air
bubble detector 188 detects an air bubble within the venous patient
line 108. Such an arrangement helps to ensure that no air bubbles
reach the patient in the event that the air release device 112
fails to remove one or more air bubbles from the blood. In some
implementations, the occluder 190 is a solenoid based ram.
Alternatively or additionally, other types of automated occluders
can be used.
[0097] Referring briefly to FIG. 1, a drug pump 192 also extends
from the front of the hemodialysis machine 102. The drug pump 192
is a syringe pump that includes a clamping mechanism configured to
retain the syringe 178 of the blood component set 104. The drug
pump 192 also includes a stepper motor configured to move the
plunger of the syringe 178 along the axis of the syringe 178. A
shaft of the stepper motor is secured to the plunger in a manner
such that when the stepper motor is operated in a first direction,
the shaft forces the plunger into the syringe, and when operated in
a second direction, the shaft pulls the plunger out of the syringe
178. The drug pump 192 can thus be used to inject a liquid drug
(e.g., heparin) from the syringe 178 into the blood circuit via the
drug delivery line 174 during use, or to draw liquid from the blood
circuit into the syringe 178 via the drug delivery line 174 during
use.
[0098] As discussed in more detail below, as an alternative to or
in addition to using a drug-containing syringe in combination with
a syringe pump to inject liquid drug into the blood circuit or to
draw liquid our of the blood circuit, the system can be adapted to
pump liquid drug into the blood circuit from a drug vial and/or to
draw liquid out of the blood circuit and into a vial.
[0099] The level detector 182, the pressure transducers 184, 186,
the touch screen 118, and the speaker 122 are connected to a
control unit (e.g., a microprocessor) of the hemodialysis machine
102. These devices can be connected to the microprocessor in any
manner that permits signals to be transmitted from the devices to
the microprocessor and vice versa. In some implementations,
electrical wiring is used to connect the microprocessor to the
instruments. Wireless connections can alternatively or additionally
be used. As described below, the microprocessor can activate an
audio and visual alarm using the speaker 122 and the touch screen
118 upon receiving signals indicating that the liquid level
detected by the level detector 182 is outside a desired liquid
level range and/or upon receiving signals that the pressure sensed
by the pressure transducer 186 is outside a desired pressure range.
Liquid levels and pressures detected to be outside of a desired
range, as discussed in greater detail below, can indicate that the
air release device 112 (e.g., the vent assembly 114 of the air
release device 112) is not functioning properly.
[0100] Still referring to FIG. 1, the dialysate circuit is formed
by multiple dialysate components and dialysate lines positioned
inside the housing of the hemodialysis machine 102 as well as the
dialyzer 110, a dialyzer inlet line 200, and a dialyzer outlet line
202 that are positioned outside of the housing of the hemodialysis
machine 102. The dialyzer inlet line 200 includes a connector
adapted to connect to one end region of the dialyzer 110, and the
dialyzer outlet line 202 includes a connector adapted to connect to
another end region of the dialyzer 110.
[0101] FIG. 10 is a schematic showing the flow paths of fluids
into, through, and out of the blood circuit and the dialysate
circuit of the hemodialysis system 100. Referring to the right side
of FIG. 10, the dialysate components of the dialysate circuit that
are located inside the housing of the hemodialysis machine 102
include a first dialysate pump 204, a balancing device 206, a
pressure sensor 208, an equalizing chamber 210, a second dialysate
pump 212, and an ultrafiltration pump 214. These dialysate
components are fluidly connected to one another via a series of
dialysate lines 216.
[0102] The dialysate pump 204 is capable of pumping dialysate to
the balancing chamber 206 via the dialysate supply line 126. In
some implementations, the dialysate pump 204 is a peristaltic pump.
However, any various other types of pumps can alternatively or
additionally be used. Examples of other suitable types of pumps
include diaphragm pumps and gear pumps.
[0103] The balancing device 206 includes a spherical chamber that
is divided into a first chamber half 218 and a second chamber half
220 by a flexible membrane 222. As fluid flows into the first
chamber half 218, fluid is forced out of the second chamber half
220, and vice versa. This balancing device construction helps to
ensure that the volume of fluid entering the balancing device 206
is equal to the volume of fluid exiting the balancing device 206.
This helps to ensure that the volume of fresh dialysate entering
the dialysate circuit is equal to the volume of spent dialysate
exiting the dialysate circuit when desired during treatment, as
described in greater detail below.
[0104] During hemodialysis, the dialysate exiting the second
chamber half 220 is directed through the dialyzer 110 toward the
equalizing chamber 210. The pressure sensor 208 located along the
dialysate line 216 connecting the dialyzer 110 to the equalizing
chamber 210 is adapted to measure the pressure of the spent
dialysate exiting the dialyzer 110. Any of various different types
of pressure sensors capable of measuring the pressure of the spent
dialysate passing from the dialyzer 110 to the equalizing chamber
210 can be used.
[0105] The spent dialysate collects in the equalizing chamber 210.
The dialysate pump 212 is configured to pump the spent dialysate
from the equalizing chamber 210 to the first chamber half 218 of
the balancing device 206. In some implementations, the dialysate
pump 212 is a peristaltic pump. However, any various other types of
pumps can alternatively or additionally be used. Examples of other
suitable types of pumps include diaphragm pumps and gear pumps. As
the first chamber half 218 of the balancing device 206 fills with
the spent dialysate, fresh dialysate within the second chamber half
220 is expelled toward dialyzer 110. Subsequently, as the second
chamber half 220 is refilled with fresh dialysate, the spent
dialysate within the first chamber half 218 is forced through the
drain line 128 to the drain.
[0106] The ultrafiltration line 129 is connected to an outlet of
the equalizing chamber 210. The ultrafiltration pump 214 is
operatively connected to the ultrafiltration line 129 such that
when the ultrafiltration pump 214 is operated, spent dialysate can
be pulled from the equalizing chamber 210 and directed to the drain
via the ultrafiltration line 129. Operation of the ultrafiltration
pump 214 while simultaneously operating the dialysate pump 212
causes increased vacuum pressure within the dialysate line 216
connecting the equalizing chamber 210 to the dialyzer 110, and thus
creates increased vacuum pressure within the dialyzer 110. As a
result of this increased vacuum pressure, additional fluid is
pulled from the blood circuit into the dialysate circuit across the
semi-permeable structure (e.g., semi-permeable membrane or
semi-permeable microtubes) of the dialyzer 110. In certain
implementations, the ultrafiltration pump 214 is a peristaltic
pump. However, any various other types of pumps can alternatively
or additionally be used. Examples of other suitable types of pumps
include diaphragm pumps and gear pumps.
[0107] Referring to FIGS. 1 and 10, a method of preparing the
hemodialysis system 100 for hemodialysis treatment will now be
described. Before hemodialysis treatment is initiated, saline is
introduced from the saline bag 176 into the blood circuit via the
saline delivery line 172 in order to prime the blood circuit. To
draw the saline from the saline bag 176 into the blood circuit, a
valve along the saline delivery line 172 is opened, a valve along
the dialysate supply line 126 is closed, and the blood pump 132 is
turned on. The saline enters the blood circuit via the pump line
adaptor 158 (shown in FIGS. 3 and 4) and then flows through the
U-shaped blood line 160 that engages the blood pump 132. The blood
pump 132 forces the saline through the blood circuit toward the
dialyzer 110. The saline flows through the dialyzer 110 and exits
the dialyzer 110 via the dialyzer outlet line 170. As the saline
flows through the dialyzer outlet line 170 toward the air release
device 112, the saline passes through the venous pressure sensor
capsule 156. Next, the saline flows through the entry port 142 of
the air release device 112 and fills the chamber 116 of the air
release device 112. To fill the chamber 116 completely, the venous
patient line 108, which leads away from the air release device 112,
is clamped while the saline is forced into the chamber 116. If the
vent assembly 114 of the air release device 112 is functioning
properly, air is forced out the top of the chamber 116 and through
the vent assembly 114 as saline fills the chamber 116. The saline
does not pass through the vent assembly 114 if the vent assembly
114 is functioning properly because the membrane 148 of the vent
assembly 114 is hydrophobic.
[0108] If the vent assembly 114 of the air release device 112 is
not functioning properly, air within the blood circuit may not be
allowed to escape from the chamber 116 of the air release device
112 during use. Such an improperly functioning air release device
112 might not be noticed during the priming procedure. For example,
if a relatively small volume of air is within the blood circuit
when the priming occurs, that small volume of air, which would get
trapped in the chamber 116 of the air release device 112, might go
unnoticed by the operator of the hemodialysis system 100.
Therefore, it is advantageous to test the operability of the air
release device 112 after priming and before treatment.
[0109] In order to test the air release device 112, the blood pump
132 is turned off, the venous patient line 108 is clamped, and the
ultrafiltration pump 214 is started. Because the blood pump 132 is
turned off, the blood pump 132 acts as a closed clamp on the
arterial patient line 106. Therefore, the blood circuit acts as a
substantially closed fluid circuit with the vent assembly 114 of
the air release device 112 being the only point of entry and exit
for air or other gases. The vacuum pressure created across the
semi-permeable structure of the dialyzer 110 by running the
ultrafiltration pump 214 causes saline to be pulled from the blood
circuit to the dialysate circuit. Because the arterial and venous
patient lines 106, 1.08 are clamped, the only fluid access to the
blood circuit is through the vent assembly 114 of the air release
device 112. Therefore, if the vent assembly 114 of the air release
device 112 is functioning properly, air will be pulled across the
vent assembly 114 and into the chamber 116 of the air release
device 112 due to the vacuum pressure. The ultrafiltration pump 214
continues to run until a sufficient vacuum is applied to the
dialysate circuit to draw enough air into the air release device
112 (assuming a properly functioning air release device 112) to
activate the level detector 182. In other words, the
ultrafiltration pump 214 continues to run until a sufficient amount
of air would be pulled through the vent assembly 114 of a properly
functioning air release device 112 to cause the saline level within
the air release device 112 to drop below the level of the level
detector 182. Typically, the ultrafiltration pump 214 is operated
in a manner to draw a sufficient amount of air into a properly
functioning air release device to activate the level detector 182
without drawing so much air into the blood circuit that the air
reaches the venous patient line 108 causing, the air bubble
detector 188 and occluder 190 to be activated.
[0110] Various different parameters affect the volume of air pulled
into the chamber 116 of a properly functioning air release device
112. For example, the operation time of the ultrafiltration pump
214, the pump speed of the ultrafiltration pump 214, the
permeability of the vent assembly 114 of the air release device
112, etc. dictate the volume of air pulled into the air release
device 112. In some implementations, the ultrafiltration pump 214
is operated for about ten seconds to about one minute (e.g., about
30 seconds) during the test procedure. In certain implementations,
the ultrafiltration pump is operated to pump fluid at a rate of
about 1 L/hr to about 4 L/hr (e.g., about 2 L/hr to about 3
L/hr).
[0111] As air is drawn into the chamber 116 of the air release
device 112, the liquid level within the chamber 116 drops. When the
liquid level drops below the level at which the level detector 182
is positioned, the level detector 182 will no longer detect liquid
in the chamber 116 of the air release device 112. As a result, the
level detector 182 will transmit a signal to the microprocessor,
indicating the absence of liquid in the air release device 112 at
the height of the level detector 182. If the level detector 182
detects the absence of liquid in the chamber 116 of the air release
device 112 after running the ultrafiltration pump 214 for the
desired time and at the desired speed, this indicates that the air
release device 112 is functioning properly. If, however, the level
detector 182 still detects liquid in the chamber 116 of the air
release device 112 after running the ultrafiltration pump 214 for
the desired time and at the desired speed, this indicates that the
air release device 112 is not functioning properly. The
microprocessor of the hemodialysis machine 102 is configured to
activate a visual and audio alarm upon receiving signals from the
level detector 182 that the liquid level within the chamber 116 has
not dropped below the level of the level detector 182 after
operating the ultrafiltration pump 214 for the desired time and at
the desired speed. In particular, the microprocessor transmit
signals to the touch screen 118 and the speaker 122, causing the
touch screen 118 to emit a visual signal and the speaker 122 to
emit an audio signal. These visual and audio signals alert the
operator of the system 100 to the possibility of a malfunctioning
air release device 112 (e.g., a malfunctioning vent structure 114
of the air release device 112).
[0112] After determining whether the air release device 112 is
functioning properly, any air that was drawn into the air release
device 112 is forced back out to the atmosphere. To do this, the
ultrafiltration pump 214 is turned off and the blood pump 132 is
turned on. Because the venous patient line 108 is still clamped at
this time, the operation of the blood pump 132 builds a substantial
amount of pressure within the blood circuit. This pressure forces
the air within the chamber 116 of the air release device 112 to
exit the chamber 116 via the vent assembly 114 of the air release
device 112.
[0113] If it was determined that the air release device 112 was not
functioning properly during the test procedure, then the air
release device 112 can be replaced or repaired. In some
implementations, for example, the operator may simply disconnect
all of the blood lines and blood components of the blood component
set 104 and discard that entire blood component set 104. A new
blood component set 104 would then be connected to the hemodialysis
machine 102. Alternatively, the air release device 112 alone could
be disconnected from the carrier body 134 of the blood component
set 104 and replaced with a new air release device 112. As another
alternative, the vent assembly 114 of the malfunctioning air
release device 112 could be removed from the air release device 112
and replaced with a new vent assembly 114. The air release device
112 with the new vent assembly 114 would then be reconnected to the
remainder of the blood component set 104. After replacing or
repairing the air release device 112, the priming and testing
processes described above would be repeated prior to beginning
hemodialysis treatment.
[0114] In some implementations, the microprocessor of the
hemodialysis machine 102 is adapted to disable certain functions of
the hemodialysis machine 102 until the operator of the system 100
indicates that the malfunctioning air release device 112 has been
replaced or repaired or until the hemodialysis machine 102 itself
is able to confirm that the malfunctioning air release device 112
has been replaced or repaired (e.g., by detecting an acceptable
level of liquid within the chamber 116 of the air release device
112 during a subsequent test). The functions that are disabled by
the microprocessor can, for example, be functions required to carry
out hemodialysis treatment. Disabling these features can help to
ensure that treatment is not performed using a blood component set
with a malfunctioning air release device.
[0115] After priming the blood circuit and confirming that the air
release device 112 is functioning properly, the arterial and venous
patient lines 106, 108 are connected to a patient 250, as shown in
FIG. 11, and hemodialysis is initiated. During hemodialysis, blood
is circulated through the blood circuit (i.e., the various blood
lines and blood components, including the dialyzer 110, of the
blood component set 104). At the same time, dialysate is circulated
through the dialysate circuit (i.e., the various dialysate lines
and dialysate components, including the dialyzer 110).
[0116] Focusing first on the blood circuit shown on the left side
of FIG. 11, during hemodialysis, the blood pump 132 is activated
causing blood to circulate through the blood circuit. The blood
follows the same basic route as the route of the saline described
above and, for the most part, pushes the residual saline in the
blood circuit through the various blood components and blood lines
and back to the patient. The blood is drawn from the patient 250
via the arterial patient line 106 and flows to the arterial
pressure sensor capsule 154. The arterial pressure sensor 184 on
the front face of the module 130 (shown in FIG. 9) aligns with the
pressure sensor capsule 154 and measures the pressure of the blood
flowing through the blood circuit on the arterial side. The blood
then flows through the U-shaped pump line 160, which is operatively
engaged with the blood pump 132. From the pump line 160, the blood
flows to the dialyzer 110. After exiting the dialyzer 110, the
blood flows through the venous pressure sensor capsule 156 where
the pressure of the blood on the venous side is measured by the
associated pressure sensor 186 on the front face of the module 130
(shown in FIG. 9).
[0117] In certain implementations, a drug, such as heparin, is
injected into the blood via the drug delivery line 174 by
activating the drug pump 192. Injecting heparin into the blood can
help to prevent blood clots from forming within the blood circuit.
Other types of drugs can alternatively or additionally be injected
from the syringe 178 into the blood circuit. Examples of such drugs
include vitamin D and iron supplements, such as Venofer.RTM. and
Epogen.RTM..
[0118] Next, the blood flows through the entry port 142 of the air
release device 112 in which any gas, such as air, in the blood can
escape. When the blood enters the chamber 116 of the air release
device 112, the blood forces the saline at the bottom of the
chamber 116, which remains in the chamber 116 from the priming
procedure, through the exit port 144 of the air release device 112.
However, the blood does not displace all of the saline within the
chamber 116. Because of the size and shape of the chamber 116, the
blood enters the chamber 116 and only traverses part of the height
of the chamber 116 before flowing back down and exiting the exit
port 144. The interface 152 (shown in FIG. 5) between the saline
and the blood delineates the furthest extent of the vast majority
of the blood within the chamber 116. Because blood and saline are
not immiscible, there is some amount of mixing between the two
fluids around the interface 152.
[0119] The saline substantially prevents the blood from contacting
the membrane 148 of the vent assembly 114. However, some blood can
be present in the saline without hindering treatment. That is, the
saline need not be completely free of blood for the air release
device 112 to both allow gas (e.g., from air bubbles in the blood)
to vent from the blood circuit and retain the liquid within the
blood circuit. The solution that is mostly to saline protects the
membrane 148 of the vent assembly 114 from becoming coated with
protein, which could clog the vent assembly 114 and reduce the
ability of the air release device 112 to vent air and other gases
from the chamber 116 of the air release device 112 to the
atmosphere. If the chamber 116 of the release device 112 is
sufficiently elongated, the blood does not mix with the saline at
the top portion of the chamber 116 because the saline remains
relatively stagnant as the blood flows through the chamber 116.
[0120] Any unbound gas, or air, that is in the blood, such as air
that is introduced by the dialyzer 110 or syringe 178, rises as
tiny air bubbles within the blood and saline until the air
eventually vents out through the vent assembly 114. The blood
travels up and over the dam 146 rather than straight across the
bottom of the chamber 116 and out the exit port 144. By directing
the flow of blood upwards, the blood with air is not able to flow
in and directly back out of the chamber 116 without flowing upwards
to at least a height greater then the height of the dam 146. The
surface area of the dam 146 and the inner walls of the chamber 116
encourage air, including microbubbles, to separate from the blood
and exit the blood circuit through the vent assembly 114.
[0121] After exiting the air release device 112, the blood travels
through the venous patient line 108 and back to the patient.
[0122] Turning now to the dialysate circuit illustrated on the
right side of FIG. 11, during hemodialysis, fresh dialysate is
pumped into the dialysate circuit from the dialysate container 124
via the dialysate supply line 126 by running the dialysate pump
204. The fresh dialysate enters the second chamber half 220 of the
balancing device 206. As spent dialysate enters the first chamber
half 218 of the balancing device 206, the fresh dialysate is forced
out of the second chamber half 220 and toward the dialyzer 110 via
the dialysate line 216. The dialysate passes through the dialyzer
110 at the same time that the patient's blood is passed through the
dialyzer 110 on an opposite side of the semi-permeable structure of
the dialyzer 110. As a result, toxins, such as urea, are
transferred across a permeable structure (e.g., permeable membrane
and/or permeable microtubes) of the dialyzer 110 from the patient's
blood to the dialysate, and those toxins collect in the dialysate
forming spent dialysate. The spent dialysate exiting the dialyzer
110 is circulated through the dialysate circuit to the equalizing
chamber 210. The dialysate pump 212 draws spent dialysate from the
equalizing chamber 210 and delivers it to the first chamber half
218 of the balancing device 206. As the spent dialysate fills the
first chamber half 218, fresh dialysate within the second chamber
have 220 is delivered to the dialyzer 110. As the second chamber
half 220 is subsequently refilled with fresh dialysate, the spent
dialysate within the first chamber half 218 is forced out of the
balancing device 206 and into a drain via the drain line 128. The
balancing device 206 balances the dialysate entering the dialysate
circuit with the dialysate exiting the dialysate circuit to ensure
that a substantially constant volume of dialysate remains within
the dialysate circuit when ultrafiltration is not being
performed.
[0123] In certain treatments, an ultrafiltration process is
performed to remove excess fluid from the patient's blood. During
ultrafiltration, a pressure gradient is created across the
permeable structure between the dialysate side and the blood side
of the dialyzer 110 by running the ultrafiltration pump 214. As a
result, fluid is drawn across the semi-permeable structure of the
dialyzer 110 from the blood circuit to the dialysate circuit. Spent
dialysate, including the toxins and excess fluid drawn from the
patient, is drawn from the equalizing chamber 210 by the
ultrafiltration pump 214 and is delivered to the drain via the
ultrafiltration line 129.
[0124] It is also advantageous to periodically test the vent
assembly 114 of the air release device 112 during the hemodialysis
treatment. By doing this, it is possible to detect damage that
might occur to the vent assembly 114 during treatment. For example,
such a testing procedure can be used to detect whether the membrane
148 of the vent assembly 114 has ruptured causing liquid to contact
the vent structure 150 and thus causing the vent structure 150 to
self-seal. Such a testing procedure can also be used to detect
whether protein has built up on the membrane 148 of the vent
assembly 114 due to contact with blood and, as a result,
significantly diminished the ability of the vent assembly 114 to
allow air to pass therethrough.
[0125] In order to test the air release device 112 during
hemodialysis treatment, the blood pump 132 and the dialysate pumps
204, 212 are temporarily stopped, the venous patient line 108 is
clamped, the ultrafiltration pump 214 is turned on, and the blood
level within the chamber 116 of the air release device 112 is
monitored. Typically, the test lasts no more than about 60 seconds
(e.g., no more than about 15 seconds, about 10-15 seconds), and
thus the blood pump 132 can be stopped without negatively affecting
the blood in the blood circuit. A drop in the blood level within
the chamber 116 below the level of the level detector 182 after
running the ultrafiltration pump 214 for a desired time and at a
desired speed indicates that the vent assembly 114 of the air
release device 112 is functioning properly, while a drop in the
blood level to a point above the height of the level detector 182
or no drop at all in the blood level indicates that the vent
assembly 114 is not functioning properly. If the vent assembly 114
is determined to be functioning properly, the treatment simply
resumes. If, however, the vent assembly 114 is determined to be
working improperly, the operator of the hemodialysis system 100 is
alerted via the touch screen 118 and the speaker 122 so that
remedial action can be taken. In response to such an alert, the
operator can repair or replace the air release device 112 using any
of the various techniques described above. It is advantageous for
the user to be able to repair the air release device 112 under
these circumstances by simply replacing the vent assembly 114. This
allows the user to repair the air release device 112 with only a
minor interruption to the remainder of the blood circuit, which,
contains blood during treatment.
[0126] In certain implementations, the above-described test
procedure is automated and is performed regularly throughout the
treatment. Alternatively, the control unit of the hemodialysis
machine 102 can be adapted to simply alert the user (e.g., via the
touch screen 118 and/or the speaker 122) when it is time to
manually perform the test. In some implementations, the test is
performed at least two times (e.g., at least five times) during the
treatment. The test can, for example, be performed at least every
60 minutes (e.g., every 30 minutes, every 15 minutes) throughout
the treatment.
[0127] After completing the patient's treatment, the dialysate
within the dialysate circuit is pumped to the drain using the
dialysate pump 212 and/or the ultrafiltration pump 214. The blood
component set 104 is then disconnected from the module 130 of the
hemodialysis machine 102 and discarded, and the dialysate circuit
is sterilized in preparation for a subsequent treatment.
[0128] While certain embodiments have been described above, other
embodiments are possible.
[0129] While the methods described above involve using the measured
liquid level in the air release device 112 to determine whether the
vent assembly 114 of the air release device 112 is working
properly, other techniques can alternatively or additionally be
used.
[0130] In some implementations, for example, the blood pressure
measured by the venous pressure transducer 186 is used to determine
whether the vent assembly 114 is functioning properly. If the vent
assembly 114 is not functioning properly, then a desired amount of
air would not be pulled into the blood circuit via the vent
assembly 114 when applying vacuum pressure to the chamber 116 of
the air release device 112. As a result, the pressure within the
blood circuit would decrease and the blood lines forming the blood
circuit might start to collapse. Thus, a pressure reduction
detected at the venous pressure transducer 186 of greater than a
certain value while drawing a vacuum on the chamber 116 of the air
release device 112 in the manner discussed above indicates that the
vent assembly 114 of the air release device 112 is not functioning
properly. In some implementations, for example, a pressure
reduction of about 100 mm Hg or more indicates that the vent
assembly 114 is not working properly. A pressure drop of less than
a certain value, on the other hand, indicates that the vent
assembly 114 is working properly. In certain implementations, for
example, a pressure reduction of less than about 10 mm Hg (e.g.,
about 0 mm Hg) indicates that the vent assembly 114 is working
properly or sufficiently.
[0131] In some implementations, the level detector 182 and the
venous pressure transducer 186 are used in combination to determine
whether the vent assembly 114 of the air release device 112 is
functioning properly. Thus, even if one of the level detector 182
and venous pressure transducer 186 were not working properly, a
malfunctioning vent assembly 114 could still be detected.
Alternatively, the control unit of the hemodialysis machine 102 can
be adapted so that no alarm is activated unless both the level
detector 182 and the venous pressure transducer 186 indicate that
the vent assembly 114 is not functioning properly. This can help to
ensure that a malfunctioning vent assembly 114 is not erroneously
identified to the operator of the system 100.
[0132] While the arterial pressure sensor 184 and the corresponding
arterial pressure sensor capsule 154 have been described as being
arranged upstream of the blood pump 132 to measure a pre-pump
arterial pressure, they can alternatively be positioned downstream
of the blood pump 132 to measure a post-pump arterial pressure, or
an additional arterial pressure sensor and arterial pressure sensor
capsule can be positioned downstream of the blood pump 132 to
measure a post-pump arterial pressure. In implementations in which
a post-pump arterial pressure sensor is provided, the post-pump
arterial pressure sensor can be used instead of or in addition to
the venous pressure transducer 186 to detect whether the vent
assembly 114 of the air release device 112 is functioning properly.
For example, with the venous patient line 108 clamped and the blood
pump 132 turned off, the ultrafiltration pump 214 can be operated
to draw a vacuum on the air release device 112 and the arterial
pressure sensor can monitor the pressure within the blood circuit.
Upon detecting that the pressure within the blood circuit has
dropped below a certain level, the arterial pressure sensor can
transmit a signal to that effect to the microprocessor of the
hemodialysis machine 102, which can activate an audio and/or visual
alarm to alert the operator of the system that the air release
device 112 is not functioning properly. In response, the operator
of the system can take any of the various different remedial
actions described above.
[0133] While some of the above methods use the pressure sensed at
the venous pressure transducer 186 or the pressure sensed at an
arterial pressure sensor located downstream of the blood pump 132
to determine whether the vent assembly 114 of the air release
device is working properly, in some implementations, the
trans-membrane pressure (i.e., the pressure differential between
the blood circuit and the dialysate circuit) is used to determine
whether the vent assembly 114 is functioning properly. The measured
trans-membrane can be compared with the pressure ranges discussed
above with respect to the venous and arterial pressure transducers
in order to determine whether the air release device 112 is venting
properly.
[0134] While methods discussed above involve operating the
ultrafiltration pump 214 to apply vacuum pressure to the air
release device 112, vacuum pressure can alternatively or
additionally be applied to the air release device 112 using other
techniques. In certain implementations, for example, the vacuum
pressure is applied to the air release device 112 by running the
dialysate pumps 204, 212, rather than the ultrafiltration pump 214.
In such implementations, the blood pump 132 is stopped, the venous
patient line 108 is clamped, and both of the dialysate pumps 204,
212 are operated. The dialysate pump 212, which is downstream of
the dialyzer 110, is operated at a greater speed than the dialysate
pump 204, which is upstream of the dialyzer 110. As a result, the
balancing device 206 becomes misbalanced such that more dialysate
is exiting than entering the dialysate circuit. In particular,
because the dialysate pump 204 is operated at a lower speed than
the dialysate pump 212, less dialysate is pumped into the second
chamber half 220 of the balancing device 206 than the first chamber
half 218 of the balancing device 206. This causes vacuum pressure
to be applied to the dialysate circuit.
[0135] In some implementations, the drug pump 192 is used to draw a
vacuum on the chamber 116 of the air release device 112. The drug
pump 192 is operated in a manner to draw liquid out of the blood
circuit rather than being operated in a manner to inject liquid
(e.g., drug from the syringe 178) into the blood circuit. To do
this, the drug pump 192 is simply run in the opposite direction
than it is run to deliver drug to the blood circuit. Prior to
performing the test procedure, the syringe 178 containing the
liquid drug is replaced with an empty syringe such that the liquid
pulled out of the blood circuit can be collected in the empty
syringe. To test the vent assembly 114 of the air release device
112, the blood pump 132, the dialysate pumps 204, 212, and the
ultrafiltration pump 214 are turned off, the venous patient line
108 is clamped, and the drug pump 192 is operated in a manner to
pull liquid from the blood circuit into the empty syringe. Because
the blood pump 132 is stopped thereby acting as a closed clamp
along the arterial patient line 106 and the venous patient line 108
is clamped the syringe pump 192 applies a vacuum pressure to the
chamber 116 of the air release device 112 as it pulls liquid into
the empty syringe.
[0136] In certain implementations, the blood pump 132 is operated
in a manner to apply vacuum pressure to the air release device 112.
In particular, rather than running the blood pump 132 in a forward
direction such that liquid within the blood circuit is pumped in
the direction from the arterial patient line 106 toward the
dialyzer 110, the blood pump 132 is operated in a reverse direction
such that liquid within the blood circuit is pumped in the
direction from the dialyzer 110 toward the arterial patient line
106. To draw a vacuum on the air release device 112 while operating
the blood pump 132 in the reverse direction, the venous patient
line 108 is clamped and the various pumps of the dialysate circuit
are turned off. As a result, when the blood pump 132 is operated in
the reverse direction, liquid is pulled from the chamber 116 of the
air release device 112 toward the dialyzer 110 and the blood pump
132. Because the venous patient line 108 is clamped, the causes a
vacuum to be drawn on the chamber 116 of the air release device 112
and can thus be used to test the functionality of the vent assembly
114 of the air release device 112 using any of the various
techniques described herein.
[0137] While certain methods discussed above involve clamping the
venous patient line 108 to pull a vacuum on the chamber 116 of the
air release device 112, the patient's arm to which the arterial and
venous patient lines 106, 108 can alternatively be lowered during
the test procedure. Lowering the patient's arm would decrease
venous pressure and could achieve a result similar to clamping the
venous patient line 108.
[0138] While some of the above methods have been described as
temporarily halting the flow of liquid through the blood circuit or
a portion of the blood circuit while operating one of the pumps
connected to the dialysate circuit to draw a vacuum on the chamber
116 of the air release device 112, in some implementations, the
flow of liquid through the blood circuit is maintained. In such
implementations, the pump(s) connected to the dialysate circuit
that are used to draw the vacuum (e.g., the dialysate pumps 204,
212 or the ultrafiltration pump 214) are simply operated at a high
enough rate to draw a vacuum on the blood circuit notwithstanding
the flow of liquid through the blood circuit. Similarly, for those
methods above that describe halting the flow of liquid through the
dialysate circuit while the blood pump 132 or the drug pump 192 are
operated in reverse to pull a vacuum on the chamber 116 of the air
release device 112, it should be appreciated that the flow of
liquid through the dialysate circuit need not be stopped. In such
cases, the flow of liquid through the dialysate circuit would
increase the vacuum pressure applied to the chamber 116 of the air
release device 112.
[0139] While certain methods above involve forcing air out of the
chamber 116 of the air release device 112 by running the blood pump
132 with the venous patient line 108 clamped, other techniques can
alternatively or additionally be used to force air out of the air
release device 112. For example, in those implementations in which
the drug pump 192 is operated in reverse to pull a vacuum on the
chamber of the air release device 112, the syringe pump could
subsequently be operated in the normal direction with the venous
patient line 108 clamped. This would cause any liquid drawn into
the syringe by running the drug pump 192 in reverse to be forced
back into the blood circuit and would create a positive pressure
within the blood circuit. As a result, any air within the chamber
116 of the air release device 112 would be expelled to the
atmosphere via the vent assembly 114.
[0140] As another example, the dialysate pumps 202, 214 and/or the
ultrafiltration pump 214 can be operated in reverse with the venous
patient line 108 clamped in order to create a positive pressure
within the blood circuit and force any air within the chamber 116
of the air release device 112 to the atmosphere via the vent
assembly 114.
[0141] While the methods described above involve activating an
audio alarm and visual arm in response to detecting a
malfunctioning device, an audio alarm alone or a visual alarm alone
can alternatively be used to alert the operator of the system to
the malfunctioning device.
[0142] While certain visual alarms have been described as being
displayed via the touch screen 118, the visual alarms can be
displayed using other types of devices. For example, in
implementations in which the dialysis machine includes a
traditional screen (i.e., a non-touch screen) along with a separate
device, such as a keyboard, for inputting data, the visual alarm
can be displayed via the traditional screen.
[0143] While the level detector 182 has been described as an
ultrasonic device configured to emit and receive ultrasonic
signals, any of various other types of devices capable of detecting
a level of liquid within the chamber 116 of the air release device
112 can be used. Examples of such devices include, among other
things, light sensors.
[0144] While the module 130 has been described as including
pressure transducers 184, 186 to detect fluid pressure within the
blood circuit, any of various other types of pressure sensors can
be used to measure this fluid pressure. In some implementations,
for example, inline pressure transducers configured to measure
positive and negative pressure on the line itself may be used.
[0145] While the drug pump 192 has been described as a syringe
pump, other types of drug pumps can be used. In certain
implementations, for example, the drug pump is a peristaltic pump.
During use of such a peristaltic pump, a drug delivery line of a
blood component set is connected to a drug vial (e.g., a heparin
vial) and operatively positioned within a housing of the pump in a
manner such that rolling members of the pump operatively engage the
drug delivery line. The pump can be operated in a first direction
to inject the drug into the blood passing through the blood lines
of the blood component set. Alternatively, the drug delivery line
can be connected to an empty vial or a drain and the pump can be
operated in an opposite direction to draw liquid passing through
the blood lines into the vial or drain via the drug delivery
line.
[0146] While the vent assembly 114 of the air release device 112
has been described as including the membrane 148 and vent structure
150, other types of vents can be used. In some implementations, for
example, the vent of the air release device includes only the
membrane.
[0147] In some implementations, the air release device 112 and at
least one of the other blood components and blood lines (e.g., all
of the other blood components and blood lines) are incorporated
into an integrated blood component set. The various components of
the integrated blood circuit can be formed together in one assembly
or integrated molding rather than discrete separate or modular
devices. The integrated blood component set can be adapted to
removably seat into the module 130 of the hemodialysis machine 102
in a manner similar to the blood component set 104 described
above.
[0148] While the various blood components have been described as
being either secured to the carrier body 134 or incorporated into
an integrated blood component set, the blood components can
alternatively be connected to one another by blood lines alone. In
such implementations, the blood components would be individually
secured to the hemodialysis machine 102 (e.g., the module 130 of
the hemodialysis machine 102) prior to treatment. The functionality
of the blood components would be similar to the functionality of
those blood components discussed above.
[0149] While the dialysate circuit has been described as being
partially integrated with the hemodialysis machine 102, the
dialysate circuit can alternatively be formed by a dialysate
component set that can be removably secured to a hemodialysis
machine during use. In some implementations, the dialysate
component set is in the form of a cassette that can be inserted
into a drawer of the hemodialysis machine in a manner such that the
cassette operatively engages components of the hemodialysis machine
when the drawer is closed. Such a dialysate component sets is
described, for example, in U.S. Patent Application No. 61/231,220,
entitled "Dialysis Systems, Components, and Methods" and filed on
Aug. 4, 2009, which is incorporated by reference herein.
[0150] While the hemodialysis machine 102 has been described as
including a touch screen, it should be appreciated that any of the
hemodialysis machines described herein can alternatively be
provided with a conventional screen and an associated control panel
or keyboard to allow the user to input data. Alternatively or
additionally, the hemodialysis machine can be equipped with a
scratch pad and/or touch buttons that permit the user to input
data.
[0151] While the various instruments that the cooperate with the
blood components and blood lines to cause blood flow and monitor
blood flow through the blood circuit has been described as being
part of a module of the hemodialysis machine, it should be
appreciated that these instruments could be integrated into the
hemodialysis machine.
[0152] While the test methods described above have been discussed
with respect to air release devices in hemodialysis systems,
similar methods can be used to test other types of devices that
include vents to allow air and/or other gases to enter and/or exit
the devices. FIG. 12, for example, is a schematic of a hemodialysis
system 302 that includes a hemodialysis machine 302 to which a
blood component set including a pre-pump arterial pressure sensor
assembly 320, a post-pump arterial pressure sensor assembly 320',
and a venous pressure sensor assembly 420 is connected. Each of the
pressure sensor assemblies 320, 320', 420 includes a fluid line
including a pressure transducer protector 340, 340', 440. The
pressure sensor assemblies 320, 320', 420 include pressure
transducers 330, 330', 430 that are secured to the hemodialysis
machine 302. Each of the transducer protectors 340, 340', 440
includes a body that forms a fluid pathway and a vent assembly
positioned along the fluid pathway. This arrangement allows gas
(e.g., air) to pass through the vent assemblies of the transducer
protectors 340, 340', 440, while inhibiting the passage of blood
therethrough. As a result, the pressure transducers 330, 330', 430
do not come into contact with blood during treatment. The pressure
transducers 330, 330', 430 measure changes in air pressure, which
can be used to determine the pressure of the blood within the blood
circuit.
[0153] The vent assemblies of the transducer protectors 340, 340',
440 help to protect the pressure transducers 330, 330', 430, and
the dialysis machine 302 on which those transducers are mounted,
from direct contact with blood flowing within the blood circuit.
Vent assemblies similar to those discussed herein with respect to
the air release devices can be used in the transducer protectors
340, 340', 440. In some implementations, each of the vent
assemblies includes a microporous membrane (similar to the membrane
148 described above) and a self-sealing vent structure (similar to
the vent structure 150 described above) that is positioned between
the microporous membrane and the pressure transducer 330, 330', 430
and is designed to automatically seal shut upon coming into contact
with blood. Thus, should the microporous membrane rupture and allow
blood to pass therethrough, the vent structure will seal and will
thus inhibit (e.g., prevent) the dialysis machine 302 from becoming
contaminated.
[0154] During hemodialysis, blood flows from the patient 250
through the arterial patient line 106 to a drip chamber 315. Blood
drips into the drip chamber 315 where a connecting tube from the
drip chamber 315 connects to the hemodialysis machine 302 via the
pre-pump arterial pressure sensor assembly 320. The blood pump 132
is used to pump the blood from the drip chamber 315 to the dialyzer
110. The post-pump arterial pressure assembly 320' is connected to
the blood line leading from the blood pump 132 to the dialyzer 110.
The pre-pump arterial pressure sensor assembly 320 and post-pump
arterial pressure sensor assembly 320' are used to determine the
pressure of the blood on the arterial side of the blood circuit.
After passing through the dialyzer 110, the blood flows to the air
release device 112 in which gas (e.g., air) in the blood can escape
before the blood continues to the patient 250. The venous pressure
sensor assembly 420 is connected to the blood line leading from the
dialyzer 110 to the air release device 110. The venous pressure
sensor assembly 420 is used to determine the pressure of the blood
on the venous side of the blood circuit. After leaving the air
release device 110, the blood travels through the venous patient
line 108 and back to the patient 250.
[0155] It is beneficial to test the functionality of the vent
assemblies of the transducer protectors 340, 340', 440 before
treatment begins (e.g., right after priming the blood circuit)
and/or during treatment. To determine whether the vent assemblies
of the transducer protectors 340, 340', 440 are functioning
properly, methods similar to those discussed above can be used.
[0156] To test the vent assemblies of the transducer protectors
340', 440, the pressure sensor assembly 320', 420 including the
transducer protector 340', 440 to be tested is disconnected from
the dialysis machine 302 and a vacuum pressure is applied to the
transducer protector 340', 440 to be tested. While applying vacuum
pressure to the transducer protector 340', 440 being tested, the
pressure within the blood circuit is monitored by the other of the
pressure sensor assemblies 320', 420, which remains connected to
the dialysis machine 302, to determine whether air is being pulled
through the vent assembly as a result of the vacuum pressure. If
air is being pulled through the vent assembly, the pressure within
the blood circuit, as detected by the pressure transducer 330', 430
of the connected pressure sensor assembly 320', 420, will remain
within a desired pressure range and this will indicate that the
vent assembly is functioning properly. If air is not being pulled
through the vent assembly, the pressure within the blood circuit
will drop below a minimum desired pressure and this will indicate
that the vent assembly is not functioning properly.
[0157] Any of the various vacuum generating techniques described
above can be used to apply vacuum pressure to the transducer
protectors 340', 440. For example, the blood pump 132 can be turned
off, the venous patient line 108 or the line connecting the
dialyzer 110 to the air release device 112 can be clamped off, and
the ultrafiltration pump and/or dialysate pumps in the dialysate
circuit can be operated to draw fluid from the blood circuit to the
dialysate circuit and thus create vacuum pressure within the
portion of the blood circuit between the blood pump 132 and the
clamp. Alternatively or additionally, the blood pump 132 and/or the
drug pump can be operated in reverse while the venous patient line
108 or the line connecting the dialyzer 110 to the air release
device 112 is clamped.
[0158] To test the vent assembly of the transducer protector 340, a
vacuum pressure is applied to the transducer protector 340 by
clamping the arterial patient line 106 and operating the blood pump
132 to draw fluid out of the drip chamber 315 toward the blood pump
132. At the same time, a level detector on the hemodialysis machine
is used to detect the liquid level within the drip camber 315. The
level detector and the drip chamber 315 can, for example, be
arranged in a manner similar to the level detector 182 and the air
release device 112. If air is being pulled through the vent
assembly of the transducer protector 340, the liquid level within
the drip chamber 315 will drop below the height of the level
detector. This will indicate that the vent assembly is functioning
properly. If air is not being pulled through the vent assembly, the
liquid level within the drip chamber 315 will remain at or above
the height of the level detector. This will indicate that the vent
assembly is not functioning properly.
[0159] While the above testing methods have been described with
respect to hemodialysis systems, similar methods can be used to
test vented devices of any of various other types of systems,
including peritoneal dialysis systems, blood transfusion systems,
cardiopulmonary bypass systems, drug infusion systems, etc.
[0160] Other embodiments are within the scope of the following
claims.
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